{Reference Type}: Journal Article
{Title}: Serological cross-reactivity between spotted fever and typhus groups of rickettsia infection in Japan.
{Author}: Aita T;Sando E;Katoh S;Hamaguchi S;Fujita H;Kurita N;
{Journal}: Int J Infect Dis
{Volume}: 130
{Issue}: 0
{Year}: May 2023
{Factor}: 12.074
{DOI}: 10.1016/j.ijid.2023.03.012
{Abstract}: <B>OBJECTIVE: </B>We examined the frequency of cross-reactions to Rickettsia typhi in patients with Japanese spotted fever (JSF) and evaluated the differences between two rickettsiae using antibody endpoint titers.<BR><B>METHODS: </B>Patients' immunoglobulin (Ig)M and IgG titers against Rickettsia japonica and Rickettsia typhi in two phases were measured using an indirect immunoperoxidase assay at two reference centers for rickettsiosis in Japan. Cross-reaction was defined as a higher titer against R. typhi in convalescent sera than in acute sera among patients fulfilling the criteria for JSF diagnosis. The frequencies of IgM and IgG were also evaluated.<BR><B>RESULTS: </B>Approximately 20% of cases showed positive cross-reactions. A comparison of antibody titers revealed the difficulty in identifying some positive cases.<BR><B>CONCLUSIONS: </B>Cross-reactions of 20% in serodiagnosis may lead to the misclassification of rickettsial diseases. However, with the exception of some cases, we were able to successfully differentiate JSF from murine typhus using each endpoint titer.